[cfe-dev] How clang works, whant to learn compiler internals

[Aleksei Sidorin via cfe-dev]

Ivan,

-Xclang option is  for passing arguments  to clang directly (like for 
'-cc1'-style call). With "-cc1" specified you don't  need -Xclang, just 
-cc1 -std=c++1z -ast-dump -fsyntax-only test_deb.cpp.


18.10.2016 11:58, Ivan Kush via cfe-dev пишет:
> thanks a lot!
> with "-cc1" the compiler doesn't understand "-Xclang" parameter.
>
>     -cc1 -std=c++1z -Xclang -ast-dump -fsyntax-only test_deb.cpp
>
> So deleted "-Xclang", but in that case AST doesn't output to console.
>
>     -cc1 -std=c++1z -ast-dump -fsyntax-only test_deb.cpp
>
> Does someone know what parameters should pass in that case, in order 
> to output AST to console?
> -- 
> Best wishes,
> Ivan Kush
> 18.10.2016, 11:12, "Serge Pavlov" <sepavloff at gmail.com>:
>> You need to pass argument "-cc1" to the compiler in debug session. In 
>> your case parameters must be:
>> -cc1 -std=c++1z -Xclang -ast-dump -fsyntax-only test_deb.cpp
>> Without "-cc1" clang works as driver executing other tools to make 
>> job, with "-cc1" it works as compiler.
>> Thanks,
>> --Serge
>> 2016-10-18 14:54 GMT+07:00 Ivan Kush via cfe-dev 
>> <cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>>:
>>
>>     I want to learn clang internals and how it works. But
>>     llvm::sys::ExecuteAndWait executes in the debugger and that's
>>     all, finish, console output with my AST (I passes to clang
>>     "-ast-dump"). It didn't jump in the Lexer.cpp, Sema.cpp, etc.
>>     What should I do in the debugger, in order to see how Lexer, Sema
>>     work?
>>     My steps in the debugger:
>>     1) compiled debug version of llvm and clang
>>     2) created a source file "test_deb.cpp" with  the following code
>>     enum class Enum : int
>>     {
>>         kOne,
>>         kTwo
>>     };
>>     int f(int x) {
>>       int result = (x / 42);
>>       return result;
>>     }
>>     int main()
>>     {
>>         return f(4);
>>     }
>>     3) launch clang-4.0 in in the debugger with the following parameters:
>>     -std=c++1z -Xclang -ast-dump -fsyntax-only test_deb.cpp
>>     4)  and begin to learn how all work:
>>     the "int main" in driver.cpp
>>     in driver.cpp is called "ExecuteCompilation" of "Driver"
>>         TheDriver.ExecuteCompilation(*C, FailingCommands);
>>     where called "ExecuteJobs" of "Compilation" (the file
>>     Compilation.cpp):
>>         C.ExecuteJobs(C.getJobs(), FailingCommands);
>>     in the func ExecuteJobs called ExecuteCommand
>>         if (int Res = ExecuteCommand(Job, FailingCommand)) {
>>     that calls "Execute" of "Command" (the file Jobs.cpp):
>>     where called a func "ExecuteAnddWait" of  "llvm::sys"
>>         return llvm::sys::ExecuteAndWait(Executable, Argv.data(),
>>     /*env*/ nullptr,
>>                                          Redirects, /*secondsToWait*/ 0,
>>      /*memoryLimit*/ 0, ErrMsg,
>>      ExecutionFailed);
>>     but the "Executable" is "...path/clang-4.0" - the file, that I
>>     launched in the debugger o__O
>>     5) so llvm::sys::ExecuteAndWait(Executable,...) is called and
>>     that's all, finish, console output with my AST. It didn't jump in
>>     the Lexer.cpp, Sema.cpp, etc.
>>     What should I do in the debugger, in order to see how Lexer, Sema
>>     work?
>>     -- 
>>     Best wishes,
>>     Ivan Kush
>>
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>>
>
>
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-- 
Best regards,
Aleksei Sidorin
Software Engineer,
IMSWL-IMCG, SRR, Samsung Electronics

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